Control system



Oct. 8, 1940. JUNKINS 2217,6 10

CONTROL SYSTEM Original Filed July 9, 1937 12 Sheets-Sheet l INVENTOROct. 1940. R. D. JUNKINS 2,217,640

CONTROL SYSTEM Original Filed July 9, 1937 12 Sheets-Sheet 2 INVENTOROct. 8, 1940. R. D. JUNKINS 2,217,640

CONTROL SYSTEM Original Filed July 9, 1937 12 Sheets-Sheet 3 INVENTOR R.D. JUNKINS CONTROL SYSTEM Oct. 8; 1940.

Original Filed July 9, 1957 12 Sheets-Sheet 4 INVENTOR R. D. JUNKINS-CONTROL SYSTEM Oct; 8, 1940..

12 Sheets-Sheet 5 Original Filed July 9, 1937 INVENTOR Get. 8, 1940. a.D. JUNKINS 2,217,640

comm. syswm Original Filed Jul 9. 1957 12 Sheets-Sheet s INVENTOR MW I IOct. 8, 1940. R. D. JUNKINS CONTROL SYSTEM Original Filed July 9, 193712 Sheets-Sheet 7 Oct. 8, 1940. R. D. JUNKINS 2,217,640

CONTROL SYSTEM Original Filed July 9, 1937 12 Sheets-Sheet 8 FIG. l0

INVENTdR Oct. 8, 1940..

R. D. JUNKINS CONTROL SYSTEM 12 Sheets-Sheet 9 Original Filed July 9,1937 mm QM: ng 1 W we u! o! INVENTOR Oct. 8, 1940. R. D. JUNKINS CONTROLSYSTEM 7 Original Filed July 9, 1937 12 Sheets-Sheet 10 INVENTOR R. D.JUNKINS CONTROLYSYSTEM Oct. 8; 1940.

Original Filed July 9, 1957 12 Sheets-Sheet 11 INVENTO'R Oct. 8, 1940.R. o. JUNKINS CONTROL SYSTEM Original Filed July 9. 19:57

12 Sheets-Sheet 12 INVENTOR Gil Patented Oct. 8, 1940 CONTROL SYSTEMRaymond D. Junkins, Cleveland Heights, Ohio,

assignor to Bailey Meter Company, a corporation of Delaware Originalapplication July 9, 1937, Serial No. 152,858. Divided and thisapplication July 20,

1938, Serial No. 220,319

13 Claims.

This invention relates to the art of measuring and/or controlling themagnitude of a variable quantity, condition, relation, etc., andparticularly such a variable condition as the density of a liquid-vapormixture, although the variable may be temperature, pressure, or anyphysical, chemical, electrical, hydraulic, thermal, or othercharacteristic.

My invention is particularly directed to a variable condition such as,for example, the density of a flowing fluid under treatment. Thevariation in the flowing fluid under treatment may be epitomized as acondition change and, for the purpose of this application, it will beunderstood that a condition change may be either a physical or chemicalchange, or both, and that the method hereinafter outlined and theapparatus specified is designed to be eflective for all such conditions.

Condition change refers to a change in the character or quality orcondition of a fluid as distinguished from a quantity change such asrate of flow, or change in a position as, for instance, movement of thefluid from one tank to another. Moreover, whenever herein the wordtreating or treatment is used, it is to be understood that any actingupon or in connection with a fluid is intended; a fluid is treated whenit is heated, when it undergoes chemical change, when two or morevarying-characteristic fluids are brought together, when a fluid iselectrolyzed, or when its degree of ionization is changed, as forinstance by dilution, change of temperature, etc., and in general, whenanything is done in connection with a fluid which is qualitative asdistinguished from quantitative.

These terms qualitative and quantitative" have reference to the broadestmeaning thereof when used in connection with a definition of what ismeant by condition change; for instance, the addition to or subtractionof heat from a fluid may merely cause it to expand or contract in sizeper unit of weight, but this change is nevertheless considered asqualitative rather than quantitative. Similarly, passage of electricalcurrent from one electrode to another immersed in a fluid is consideredto effect a qualitative change therein within this disclosure; in short,any phenomenon in a flowing fluid which so evidences itself as to bemeasured in the manner herein disclosed or in connection with a densitydeterm ination is deemed to be a condition change.

Having the foregoing in mind, it will be seen that condition changes mayoccur as the result of several difi'erent operations, sequentially orsimultaneously. For instance, considering the change in density whichoccurs in a flowing fluid, such change may be the result of the heatingof the fluid, or of an alteration in the chemical composition of thefluid without heat being imparted thereto, or of an expansion of thefluid While flowing through a treating zone, for instance by changingthe volume per unit lineal distance of the space in which the fluid istraveling, or a combination of these effects may cause changes in thedensity of a flowing fluid with consequent production of a variablewhich may be used as a basis for fluid processing control.

It should not, of course, be overlooked that similar difieringconditions may also result in variations in temperature, pressure, andthe other factors which vary in a process. Moreover, a

temperature change may occur in a fluid entirely because of internalaction and without any external subtraction or addition of heat, thatis, as

a result of chemical action.

I have chosen to illustrate and describe as a preferred embodiment of myinvention its adaptation to the measuring and controlling of the densityand other characteristics of a flowing heated fluid stream, such as theflow of hydrocarbon oil through a cracking still.

While a partially satisfactory control of the cracking operation may behad from a knowledge of the temperature, pressure and rate of flow ofthe fluid stream being treated, yet a knowledge of the density of theflowing stream at different points in its path is of a considerablygreater value to the operator, but was not available prior to thediscovery by Robert L. Rude, as disclosed in his copending applicationSerial No. 152,860 filed July 9, 1937.

In the treatment of water below the critical pressure, as in a vaporgenerator, a knowledge of pressure, temperature and rate of flow may besuiflcient for proper control, inasmuch as definite tables have beenestablished for interrelation between temperature and pressure, and fromwhich tables the density of the liquid or vapor may be determined.However, there are no available tables for mixtures of liquid andvapor.-

In the processing of a fluid, such as a petroleum hydrocarbon,. a changein density of the fluid may occur through at least three causes:

1. The generation or formation of vapor of the liquid, whether or notseparation from the liquid occurs.

2. Liberation of dissolved or entrained gases.

3. Molecular rearrangement as by cracking or polymerization.

The result is that no temperature-pressuredensity tables may beestablished for any liquid, vapor, or liquid-vapor condition of such afluid, and it is only through actual measurement of the density of thefluid, or of a mixture of the liquid and vapor, that the operatormayhave any reliable knowledge as to the physical condition of the fluidstream at various points in its treatthe art that the continuousdetermination of the density of such a flowing stream is of tremendousimportance and value to an operator in controlling the heating, meandensity, time of detention and/or treatment in a given portion of thecircuit, etc. A continuous knowledge of the density of such a heatedflowing stream is particularly advantageous where wide changes in.density occur due to formation, generation, and/or liberation of gases,with a resulting formation of liquid-vapor mixtures, velocity changes,and varying time of detention in different portions of the fluid path.In fact, for a fixed or given volume of path, a determination of themean density in that portion provides the only possibility of accuratelydetermining the time that the fluid in that portion of the path issubjected to heating 1 or treatment. By my invention I provide therequisite system and apparatus wherein a determination of suchinformation comprises the guiding means for automatic control of theprocess or treatment.

While illustrating and describing my invention as preferably adapted tothe cracking of petroleum hydrocarbons, it is to be understood that itmay be equally adaptable to the vaporization or treatment of otherliquids and in other processes. For example, in the distillation ofoils, the generation of steam, and other chemical and/or physicalprocesses, wherein a fluid is subjected to a condition change, as forexample the heating of a fluid flow path. In particular, the inventionrelates to the automatic control of the treatment process, and as aspecific example thereof I have illustrated and will describe thecontrol of the rate of flow and of the heating in a cracking still.

In the drawings:

Fig. 1 is a diagrammatic representation of density measuring apparatusfor a heated fluid rangement of combustion control.

Fig. 6 diagrammatically illustrates a control of heating andrecirculation of the products of combustion in connection with acracking still.

Figs. 7 and 8 illustrate a control. of the fluid flow in an oil refiningprocess.

Fig. 9 illustrates apparatus for guiding the control of condition changein a heated fluid path.

Fig. 10 is an arrangement for determining time of treatment and controltherefrom.

Fig. 11 illustrates diagrammatically an arrangement supplemental to Fig.10 for determining time-temperature relationship and control therefrom.

Fig. 12 is supplemental to Figs. 10 and 11 for determining yield perpass and control therefrom.

Fig. 13 diagrammatically illustrates a. control of combustion from acondition value at a plurality of points in the fiow path.

14 is a sectionah elevation in detail of a pilot valve assembly.

Fig. 15 is a diagrammatic view of a'special pilot valve construction.

an adjustable such condition change, the density of the fluid willchange so that the density at the outlet of the section which is beingheated will be different from the density at the inlet of that section.If the section in question is the conversion section in an oil crackingfurnace, the condition change brought about by the'application of heatmay be a physical change, or a chemical change, or a combination ofboth. The rate of flow of the charge of relatively untreated hydrocarbonis continuously measured by the rate of flow meter, or differentialindicator 3, while a differential indicator 4 is located with referenceto the conduit l beyond the heating means or after the flowing fluid hasbeen subjected to a condition change such as heating or otherprocessing.

While the fluid flow measuring instrumentalities 3 and 4 are illustratedand described as differential pressure responsive devices, it will beunderstood that such showing and description are illustrative only andnot to be taken in a limiting sense, because fluid flow measuringdevices such as displacement meters, volumetric meters, Thomas meters,or the like, may be used in the determination of fluid density inpracticing the invention herein disclosed.

The float-actuated meter 3 is sensitive to the difierential pressureacross an obstruction, such as an orifice, flow nozzle, Venturi tube, orthe like, positioned in the conduit for effecting a temporary increasein the velocity of the flowing fluid. Such an orifice may be inserted inthe conduit between flanges as at 5. The meter 3 is connected by pipes6, I to opposite sides of the orifice 5 and comprises a liquid sealedU-tube,' in one leg of which is a fioat operatively connected toposition an indicator 8 relative to an index 9. In similar manner theindicator ill of the meter 4 is positioned relative to an index II; themeter 4 being responsive to the differential head across an orifice orsimilar restriction between the flanges 12.

The relation between volume flow rate and differential pressure (head)is:

Q C'M /2gh (1) where eter to pipe diameter, regardless 'of the densityor specific volume of the fluid being measured. With C, M and allremaining constant, then Q varies as the 'Thus it will be seen that thefloat rise of the meters 3, l is independent of variations in density orspecific volume of the fluid at the two points of measurement and thatthe reading on the indexes 9, II of differential head is directlyindicative of volume flow. If the conduit size and orifice hole size arethe same at both meter locations, then the relation of meter readings isindicative of the relation of density and specific volume; head varyingdirectly with specific volume and inversely with density. Thus for thesame weight rate of flow past the two metering locations thedifferential head at location I2 will increase with decrease in densityof the fluid, and vice versa.

If it is desired to measure the flowing fluid in units of weight,Formula 1 becomes:

W CM /2ghd (2) where W=rate of flow in pounds per sec.

d=density in pounds per cu. ft. of the flowing fluid. h=difierentialhead in inches of a standard liquid such as water.

M=meter constant now including a correction between the density d of theflowing fluid being measured and the density of the liquid in themanometer which is some standard such as water.

Assuming the same weight rate of flow passing successively through twosimilar spaced orifices 5, I2, and with a change in density as may becaused by the heating means 2, then the density at the second orifice I2may be determined as follows:

mwm

vm= s s Thus it will be observed that, knowing the density of the fluidpassing the orifice 5, we may readily determine the density of the fluidpassing the orifice I2 from the relation of differential pressuresindicated by the meters 3, 4.

As an example of other types of fluid flow measuring devices, Iillustrate in Figs. 1A and 1B the use of displacement or volumetric typemeters in an arrangement in general like that of Fig. 1.

In Fig. 1A the volumetric or displacement type of flow meter 3A islocated in the conduit I ahead of the heating means 2, while a similarflow meter 4A is located after the flowing fluid has been subjected toheating or to other treatment.

As known, the total volume of fluid passing through a conduit in a givenlength of time is conveniently and accurately measured by positivedisplacement meters which have as a primary element a chamber orchambers through which the fluid passes in successive isolatedquantities or volumes. These quantities may be separated from the streamand isolated by alternate filling and emptying of containers of knownquantity and fluid cannot pass through without actuating the primarydevice. The secondary element of such a meter usually is a counter withsuitably graduated dials for indicating the total quantity that haspassed through the meter up to the time of reading. In Fig. 1A, however,the rotatable shaft which normally actuates such a counter is hereinadapted to drive or position the mechanism which functions to determinedensity of the fluid.

vice 3A causes rotation of the elements I58 therein, which causes thepassage of definite trapped portions of fluid through the device 3A fromthe inlet to the outlet. The operation of the device 4A is similar.

The speed of a flexible shaft I59 leaving the primary element 3A variesdirectly with rate of fluid flow, directly with variations in specificvolume of the fluid, and inversely with variations in density of thefluid. The same is true of the speed of a shaft I60 leaving the primaryelement 4A in regard to the fluid flowing therethrough.

By interrelating or comparing the speed of the shafts I59, I60 I maydetermine the relative density between the two locations, or for examplecompare the density of the fluid before the heating means 2 with itsdensity at a location after the heating means. This comparison willallow me to ascertain the change in specific volume or density, due tothe treatment or heating by the means 2, as well as to ascertain anindication of the heat change in the fluid.

While I have stated that the speed of the shaft I59 as well as the speedof the shfat I60 will individually vary with rate of flow of fluid,still if I am making a comparison of the speed of the shafts I59, I60where the same fluid passes successively through the meters 3A, 4A, thenvariations in the rate of flow will have no more effect upon the oneshaft speed than upon the other shaft speed, and may therefore bedisregarded entirely. Thus the speed of the shafts I59, I60 will varywith variations in specific volume or density at the individual meters3A, 4A.

As previously stated for the example illustrated herein, I consider thatthe fluid entering the meter 3A is the charge or relatively untreatedhydrocarbon to the furnace, and at a substantially uniform specificgravity or density. Such may be determined periodically if desired toascertain whether it has in fact departed from the design conditions forwhich the meter 3A and shaft I59 are calibrated. Assuming then for themoment that the specific gravity or density of the fluid in the conduitI entering the meter 3A remains constant, then the density of the fluidpassing through the meter 4A may be determined as follows:

where dsA=density of fluid passing through meter 3A d4ii=density offluid passing through meter 4A Si59=-,-speed of shaft I59 of meter 3ASiso=speed of shaft I60 of meter 4A This is, of course, predicted uponthe fact that the meters 3A and 4A are of the same size and design sothat if the same volume rate of fluid at the same density conditons ispassing through the two, then the speeds of the shafts I59, I60 are thesame.

As a practical means of mechanically solving the Formula 3A to determinethe density of the fluid passing through the meter 4A, I will nowdescribe in detail the showing of Figs. 1A and 1B.

A disk I6I is adapted to be rotated by the displacement meter 3A throughthe shaft I59. Frictionally engaging the disk I6I is a sphere or ballI62 likewise frictionally engaging a rotatable spool I63 supported by acarriage, I64. The spool I63 is provided with an arm I65 as shown inFig. 13 carrying a pair of contacts I66 and I61 connected throughsuitable slip rings in a drum I60 to opposed fields I69 and I10respectively of a, motor I1I.

The drum I68 is rotated by the meter 4A through the agency of the shaftI60 and carries a contact I12 cooperating with the contacts I66, I61.The contact I12 is connected through a slip ring in the drum I68directly to the power source I13 through a conductor I14. Thearrangement is such that upon engagement of the contact I12 with thecontact I 66 the field is energized and conversely upon engagement ofthe contact I12 with the contact I61 the field I10 is energized. Themotor "I is adapted to drive an indicatingrecording pen arm I15 relativeto a chart I16 through gears I11 and in unison therewith the carriageI64 through a gear I10 meshing with a suitable rack I19 carried in thecarriage I64.

In operation, assuming the system to be in equilibrium the contacts I66,I61 will be rotated at synchronous speed with the contacts I12 so thatthe fields I69, I10 of the motor H! are deenergized. Upon an increase inthe rate of firing through the burner 2 with a corresponding increase inspecific volume and conversely a decrease in density of the fluidpassing through the meter 4A, the speed of the shaft I 60 will increaserelative to the speed of the shaft I59. Thus the rotative speed of thedrum I60 and of the contact I12 will increase relative to the rotativespeed of the disk I6I, the spool I63 and the-contacts I66, I61. Thearrangement is such that the contact I12 will engage the contact I66,causing energization of the field I69 and rotation of the motor I1I inproper direction to move the carriage I64 to the right on the drawing,whereby the radius of contact of the sphere I62 with the disk I 6Irelative to the center of the disk I6I will be increased, and therebythe speed of rotation of the spool I63 and contacts I66, I61 will beincreased relative to what it was previously, and such action willcontinue until the rotative speed of the contacts I66, I 61 and thecontact I12 is in synchronism and the contact I12 is not close circuitedwith either the contact I66 or the contact I61, whereafter rotation ofthe motor I1I will cease. The position of the carriage I64 andcorrespondingly (through the gear I11) of the indicator I15 relative tothe chart I16 is indicative of the density of the fluid passing throughthe meter 4A. This may be seen from the following:

Angular travel of ltravel of 159x Radius Angular travel of 172: [travelof 160 But in equilibrium- Angular travel of 165=Angular travel of 172Therefore- Atravel of 159x Radius= Ztravel of 160 A travel of 160Atravel of 159 and- When A travel of 159 0 R= m (infinity) When 4 travelof 160=0 R=0 Thus the radial distance from the center of the disk I6I tothe point of contact of the sphere I62 with the disk I 6 I, is a measureof the ratio of the speeds of the shafts I59, I60, and knowing thedensity of the fluid passing'through the meter 3A, said radius is ameasure of the density of the fluid passing through the meter 4A. Thevalue of the density of the fluid passing through the meter 4A isindicated and recorded relative to the chart I16 by the positioning ofthe pointer I15 through the agency of the motor HI.

I have now illustrated and described two somewhat dissimilar types offlow metering devices utilized in the determination of density of aflowing fluid stream, but it doesnot seem necessary for an understandingof my invention to describe the utilization of more than a singlerepresentative type of metering device in the measuring and regulatingof fluid treatment. I have, therefore, chosen the first example, namely,that illustrated in Fig. 1 as a. representative type of fluid flowmeasuring apparatus, and which I will now describe in connection withthe remaining drawings and the arrangements illustrated thereon. It isto be understood; however, that I could readily illustrate and describethe arrangement of Figs. 1A and 13 as adapted to the variousarrangements of the subsequent sheets of drawing embodying my inventionexcept that I feel that this would be an unnecessary duplication andlengthening of both the drawing and specification.

Referring now to Fig. 2, wherein like parts bear the same referencenumerals as in Fig. 1, I indicate that after the fluid has passedthrough the orifice I2A it is returned to a further heating section ofthe still, from which-it passes through a third difierential pressureproducing orifice I3A. The heating coil I4 will be'hereinafter referredto as a first heating section, while the coil I5 will be referred to asa second heating' section. In the prelerred arrangementand op-- erationof the still the section I5 is the conversion or cracking section, andthe one in which it is primarily desirable to continuously determine themean density of the fluid, as well as the time of detention or treatmentin the section. For that reason I now desirably determine the meandensity of the fluid in the section l5 and accomplish this through aninterrelation of the differential pressures produced by the same weightflow passing successively through the orifices 5, IZA, I3A.

The same total weight of fluid must pass through the three orifices in'succession so long as there is no addition to or diversion from the pathintermediate the orifice locations. It is equally apparent that in theheating of a petroleum hydrocarbon, as by the coil I4 between theorifices 5 and I2A, there will be a change in density of the fluidbetween the two orifices, and furthermore that an additional heating ofthe fluid, as by the coil I5, will further vary the density of the fluidin the conversion section I5 is then obtained by averaging the densityof the fluid at the orifice [2A, I3A. As for example:

Thus the mean density of the flowing fluid in the conversion section l5(knowing the density or specific gravity of the fluid entering thesystem) may be directly computed from the readings of the indexes 9, ll,l8. This, of course, on the-basis that the orifices 5, IZA, I3A are thesame, and that the capacity of the float meters 3, 4, I6 is the same.

Now as the specific volume of a flowing fluid increases progressivelyfrom locations 5 to MA to I3A, the differential pressure across theseorifices increases in like manner, and in the operation of such acracking still it may be that the differential pressure across anorifice I3A will be several times that across the orifice 5 if theorifice sizes are equal. I have, therefore, indicated at I2A, l3A ofFig. 2 that these orifices may be of an adjustable type wherein theratio of orifice hole to pipe area may be readily varied externally ofthe conduit through suitable handwheel or other means. Reference may behad to Fig. 16, which shows a sectional elevation of a typicaladjustable orifice having a segmental shaped plate l9 projecting acrossthe internal area of the conduit I in varying degree depending upon thepositioning of the plate l9 through the agency of a handwheel 20,

Such an adjustable orifice per se forms no part of my present invention,and inasmuch as it is anartlcle of commerce readily obtainable in theopen market, it is not believed necessary to go into greater detail inregard to its construction and operation.

The actual orifice design in terms of pounds per hour is: v

max h r W =360 cfDH/ VOL (6) where W=lbs. per hr. D =diameter ofequivalent circular orifice hole in inches c =coefilcient of discharge f:factor of approach sp. vol.=cu. ft./lb.

Now considering that orifice {2A is so adjusted that its cJD isdifferent from that of orifice 5, we

may then determine the density at I2A as follows:

lZA CR2 where cfD In similar manner I may determine the density at theorifice ISA regardless of the orifice area, so long as I take intoaccount the cfD of the orifice in the above manner. It will thus be seenthat, if the specific volume of the flowing fluid increases so rapidlythat the differential head at successive orifice locations (for thesame'design of orifice) becomes many times the value of the difierentialhead at the initial orifice, it would be impractical to attempt toindicate or record such differential heads relative to a single index orrecord chart without one or more of the indications or records goingbeyond the capacity of the index or chart. There are two ready means ofovercoming this practical difiiculty, the first being an adjustment ofthe successive orifices, such as IZA, I3A, to have new values of c,fDsuch that the indicator or recording pen will be kept on the chart; andthe second through varying the basic capacity of the meter 4 or l6relative to the meter 3. This latter method, comprises so arranging themeter 4, for example, that it requires 50% greater differential pressureto move the related pointer over full index range than in the case ofmeter 3. This may readily be accomplished by properly proportioning thetwo legs of the mercury U-tube, on one of which the float is carried. Ofcourse it will be necessary to take such changes in capacity intoaccount when utilizing the diflerential head readings in determiningdensity or mean density.

, For example, the reading of the pointer relative to the index shouldbe on a percentage basis of whatever maximum head the meter is designedfor. Then the total head corresponding to the indicator reading will beavailable or the proper water differential to cause the indicator l0 tomove from 0 to' 100% over the index H, and H relative to IE. Then:

F; float travel of meter 3 F float travel of meter 4 substituting in('7) In Fig. 3 I show in diagrammatic fashion the actual mechanism whichI preferably employ to obtain indications of mean density, time ofdetention, etc. valuable as a guide to operation of the system and toactuate automatic control; According to Formula 5 it is necessary indetermining the mean density of the conversion section to obtain theratio of the diiferential heads at ori-. fices 5 and HA. Then to obtainthe ratio of the difierential heads at orifices 5 and 13A. To thenaverage these ratios. I accomplish this result through the use oflogarithms, a process well known in mathematics, whereby it is possibleto obtain a quotient by subtraction or a product by addition. Inconnection with logarithmically designed cams "I employ self-synchronousmotors which lend themselves readily to addition or subtraction throughdifierential windings, as well as having the feature of ready groupingat remote locations.

I indicate such self-synchronous generators for transmission of positionat 2|, 22, 23, 24, 25, 26 and 21, while the self-synchronous receivingmotors are indicated at 28, 29, 30, 3l-32, 33-34, 35-36, 3! and 38. Thetransmitting generator in each case is operated at a suitable angularrotation through the angular positioning of the rotor or single phasefield winding. The stator or armature is in each case provided with a3-phase winding. The field windings of each transmitting generator areenergized from a suitable source of alternating current supply.

The operation of systems: of this general character for the transmissionof angular movement is well known in the art. Voltages are induced inthe 3-phase stator windings of the transmitter or receiver by the singlephase field winding on the associated rotor. When the rotor of one ofthe transmitters is moved from a predetermined position with respect toits stator, a change is efiected in induced voltage in the armaturewinding and the rotor of the receiving motor assumes a position ofequilibrium relative to the transmitting generator, wherein the inducedvoltages in the 3-phase windings are equal and opposite, andconsequently no current is set up in the armature winding. If the rotorof one of the generators is turned and held in a new position thevoltage is no longer counterbalanced, whereby equalizing currents arecaused to flow in the armature windings which exert a torque on therotor of the receiving motor, causing it to take up a positioncorresponding to the position of the transmitting generator.

The receiving motors 28, 29, 30 are individually positioned insynchronism with the transmitting generators 2|, 23, 24. Between theindicator arm 8 and the transmitting generator 2| I interpose a cam 39having a rise proportional to the logarithm of its angular motion, tothe end that the receiving motor 28'and the recording indicator 40positioned thereby assume a position corresponding to log 715. Similarlythe indicator arm 4| is positioned by the receiving motor 29 inaccordance with the value of log hlZA, while the indicator 42 ispositioned in accordance with the value of log hl3A- Actually the designis such that the transmitting generator 2| (positioned in accordancewith log F3) attains maximum desired rotation 'with from 10-'100% fullfloat travel. No motion of the generator 2| occurs when the float of themeter 3 moves over -1()% of its travel range. This because it is.impossible to-have a logarithmic cam start at zero, as the number 0 hasno logarithm. Also because the logarithmic characteristics are such thatI would have as much cam rise for from 1% to 10% of float rise as from10% to 100%. Thus I may make the cam 39, and the similar cams of themeters 4 and I5, of practical size and proportion by sacrificing only.the first 10% of the float travel of the meters and with theexpectation that the operation will not normally be below 10% of fullfloat travel.

In addition to indicating and recording in inter-relation upon therecord chart 43 the values of the log of the differential pressures atthe three orifices, the position of the transmitting generators 2|, 23,24 is utilized through the agency v of difierential self-synchronousdevices to algebraically add the value of the log h for the difierentorifices and thus accomplish the ratio operation. Angular movementimparted mechanically to the rotors of the transmitting generators 2|,23 will result in an angular positioning of the rotor of the receivingmotor 3I-32. Similar action occurs between the transmitting generators2|, 24 and the receiving motor 33-34; and between the transmittinggenerators 22, 26 and the receiving motor 35-36.

The receiving motors 3l-32, 33-34, and 35-36 have 3-phase rotor,windings and 3-phase stator windings and are commonly known asdifferential self-synchronous motors, for in each case they areresponsive to two of the transmitting generators and assume a rotorposition corresponding in differential efiect from the two relatedtransmitters. For example, the receiving motor 3|-32 has its rotorpositioned responsive to a differential between the position of therotor 2| and that of the rotor 23, or according to log h5-l0g hmA, thusperforming the mathematical operation:

h log j =1og h -log It,

From Formula 5 the mean density of the fluid in the conversion sectionis the density of the fluid at orifice 5 multiplied by the average ofthe ratio of headsfor the different orifice locations |2A and |3A. Indesigning the apparatus I incorporate an average expected value ofspecific gravity or density of the fluid'at the orifice 5 in thetransmitted motion of the rotor of. 3|-32 and of the rotor 33-34. Thus,if the expected density exists at the orifice 5, the indicator moved bythe rotor of 3l-32 will indicate relative to the index 44 theinstantaneous value of log (112A, while on the index 55 may be read theinstantaneous value of log (113A.

The rotor of 3l-32 angularly moves a cam 46 having a rise proportionalto the antilog of its angular motion; likewise the rotor 33-34 angularlymoves an antilog cam ll. Thus the vertical movement of a roller at thelower end of a link 48, riding on the cam 46, is proportional to elm andthat of 49 to 4113A To obtain the mean density through the conversionsection i5 it becomes necessary to solve Formula 4, and this Iaccomplish through a differential mechanism 50 adapted to position anindicator 5| relative to an index and recording chart 52 to continuouslyrecord thereon the value of mdis.

It is to be understood that if the basic capacity of meters 3, 4, I6vary one from the other, then as previously brought out, this may betaken care of as in (8). The linkage through which the arm l0 positions23 and the linkage through which the arm I! positions 24 may incorporatethe necessary correction values. Or it might be taken into account as at(9) at the outlet side of antilog cams 46, 41. Furthermore, I haveillustrated and described the orifices |2A and |3A as tioning of cam 46upon one-half of differential 50. Thus cam 46 which is angularlymoved'propoxtional to F h log T: or log i;

will position the m. 54 relative to the index 55 according to:

12A 3- 1 or mdls At 59 I indicate a manual adjustment of the.

motion of arm 5| to take into account deviations in value of d5 of (9)from design conditions, as might be attributed to changes in specificgravity, temperature, etc.

The arm 5| is adapted to position a logarithmic cam 60 for moving atransmitter 26 proportional to log md15. for moving a transmitter 22proportional to s 1: which so long as d5 remains constant equals log Wwhere W is rate of flow in pounds. The differential motor 35-36 is thenunder the'infiuence.

Cam 6! is of antilog design and the arm 62 is moved relative to recordchart 63 to indicate the time of detention or treatment of any particleof fluid in the heating section l5, from:

where T Time any particle is in section l5. V=Volume between 12A and BA(cu. ft.) md15=Mean density (lbs. per cu. ft.) W=Rate of flow (lbs. perunit T) The position of the arm 62 is used to angularly position atransmitter 25, in' turn positioning a receiver 31 and cam 64. Closelyrelated is a cam 65 positioned by a receiver 38 under the control of atransmitter 21 responsive to mean temperature of the fluid mixture.Temperature responsive bulb 66 is located in the fluid at the outlet ofthe heating section I5, while bulb 61 is located at the inlet to thesection. The corresponding Bourdon tubes 66, 69 are arranged to positionthe transmitter 21 according to the mean temperature of the fluidthrough the section l5. The cams 64, 65 may be designed as uniform risecams or to take care of any characteristics or relationship as may bedesired. Through their interrelation an indicator 10 is continuouslypositioned relative to an index and recording chart ,H to advise thetime-temperature relationship for the conversion section I5.

An indicator pen I2 is positioned with the indicator 10 by thetime-temperature relation but is further provided with a stock factoradjustment '3 so that the pen [2 records on the chart H the yield perpass. The stock factor adjustment I3 is available to correct fordeviations in specific gravity, Anilin number, and such other variablesas may afiect the charge or fluid entering the conduit I.

In Figs. 4, 5, 6, 7, 8, 10 and 13 I indicate the The meter- 3 positionsa cam 39A various self-synchronous transmitters and receivers of Fig. 3as circles and "the numerous interconnecting wires merely by dot-dashlines for the sake of simplicity on the drawings. In Figs. 4, 5, 6, 7,8, 10, 11, 12 and 13 I indicate pipes transmitting loading air pressuresby short dash lines to avoid confusion.

Referring now in particular to Fig. 4, I show therein the conduit l as aonce through fluid heated path wherein the charge stock passes throughthe orifice 5 at the entrance to the still,

then through the adjustable orifice I2A at the entrance to theconversion section, and then through the adjustable orifice I3A attheexit of the conversion section of the still. The general arrangement,similar to Fig. 3, is adapted (on the drawing) to vertically positionthe member ll, the pointer I5 relative to the index 16, and the pivot11, in accordance with the value of mean density md15 through theconversion section l5.

A thermocouple 18 is so located. as to be sensitive to the temperatureof the flowing fluid at the entrance to the conversion section [5 andactuates a potentiometer instrument 19 for energizing a motor in onedirection or the other. The motor 80 is arranged to position anindicator pen 6| to indicate and record on a record chart 62 the valueof temperature at the location 18, and at the same time to verticallyposition a pivot point 83.

The pivot points 11, 83 form the two ends of a floating beam 84.Intermediate the ends of the beam 84 is freely suspended a pilot stem 85for controlling an air loading pressure in accordance with relationbetween mean density and temperature.

Referring now to Fig. 14, it will be observed that the pilot stem 85carries two spaced lands '66 and is axially movable relative to apassage through a housing 81. Air under pressure is.

available at the interior of the passage between air compressor. catethe available air supply by a small arrow at the side of the pilot valvehousings.

The lands 86 are in spaced relation to annular ports 88, theuppermost'of which is in communication with an outlet connection 69 andthe lowermost in communication with an outlet connection 90. Thearrangement is in general such that axial movement of the stem 85produces a gradation in pressure available at the connections 89, 90.For example, if the stem 85 is moved upwardly, then the air pressureavailable at the outlet connection 69 increases proportionally to theaxial movement, while that available at the connection decreases at thesame time. Down-' ward movement of the stem 85 causes a decrease inpressure at 89 and an increase in pressure at 90. Thus the air loadingpressure available through the outlet connections 89, 90 is definitelyrelated in direction and amount to the axial po-.

mean density varies due, for example, to change in pressure or change inrate of charge,-I estabto return mean density and yield per pass to de-Such a.pilot valve arlish a new temperature standard whose effect issired value and then I so control the firing as to maintain this newtemperature standard.

By way of example, if through pressure or rate of charge. the meandensity through the conversion section varies, then the pivot point I7is moved upwardly. This positions the pilot stem 85 and causes acorresponding variation in air loading pressure to vary the rate offiring; the air loading pressure from the pilot assembly 87 beingeffective througha pipe 9| and valves 92, 93 upon the fuel control valve94 and/or the air control mechanism 95.

Through the agency of the valves 92, 93 the air loading pressure fromthe pilot valve 81 may be effective upon either the air supply or thefuel supply, or both. when through variation in the rate of firing thetemperature at the thermocouple location I8 is varied in properdirection and amount, the new temperature effective in positioning themotor 88 moves the pivot 83 downwardly until the pilot 85 is returned toits equilibrium position. Thereafter slight variations in temperature,or in mean density, will position the pilot 85 to vary the firing inamount and direction whereby the desired temperature standard for agiven value of mean density is maintained. It is, of course, understoodthat after the new temperature standard for'the new mean density hasbeen attained this change in temperature will result in a change in meandensity to return the mean density to its original desired value, andthe new temperature necessary to maintain the mean density at that valuewill be recorded upon the chart 82.

Assume that I desire to maintain mean density and yield per passconstant. Then assume that an increase in pressure causes an increase inmean density and, for example, the pivot I'I' moves downwardly. Thispositions the pilot 85 downwardly, increasing the loading pressure inthe line SI and increasing the rate of supply of the elements ofcombustion, or the firing. The increase in firing tends to raise thetemperature at the location I8 and this results in a raising of thepivot point 83 with corresponding greater value recorded on the chart82. The raising of the pivot point 83 tends to restore the pilot 85 toits original position. At the same time, however, the increase in firingdecreases the mean density toward its original value and this causes araising of the pilot 85 to somewhat decrease the firing. The systemsettles out to a state of equilibrium wherein substantially thepredetermined mean density is maintained, but with a new temperaturestandard and the firing rate adjusted to maintain that temperaturestandard. Such a temperature standard corrects the meandensity for thevariation it felt from the othercause or causes of mean density change,such as pressure variation or variation in the rate of charge, etc.

At all times the indicator I5 will-indicate relative to the index 16 thevalue of mean density through the conversion section, while theindicator 8| records and indicates relative to the chart 82 the value oftemperature at the thermocouple location 18.

Fig. 5 is somewhat similar to Fig. 4 wherein the end 11 of the member 84is positioned in accordance with the value of mean density through theconversion section I5. The end 83 is positioned in accordance with thevalue of mean temperature through the conversion sec-- tion I5 throughthe agency of thermocouples ll, 91 which are so connected in the circuitof the potentiometer I9 as to position the pointer 8| and the pivot 83according to the mean temperature, or average temperature, throughoutthe section I5. A pilot stem 98' is vertically positioned by the member84 relative to two pilot housings.

Referring now to Fig. 15, I show in detail the arrangement of thisspecial pilot assembly wherein the outlet connection 99 leads to thefuel control valve 99 while the outlet connection I88 leads to arheostat positioner I8I controlling the speed of a fan I82 forrecirculation of the products of combustion around the bridge wall. Asthe pilot stem 98 is moved downwardly the land I83 provides a graduallyincreasing gradation in pressure available at the outlet 99.Simultaneously the downward movement of the land I88 results in agradual increase in pressure.

available at the outlet I88 until after a certain period of movement theland I85 has reached a position relative to the port I 86 that some ofthe pressure in the outlet I88 begins to bleed through the port I88 tothe atmosphere, The result is a sequentialoperation wherein continueddownward movement of the stem 98 results in a gradual increase inpressure at the outlet I88 until a certain value of pressure is reached,beyond which the pressure decreases. This action occurring while thepressure in the outlet 99 is continually increasing throughout fullrange of travel.

In Fig. 5 a valve I8'I controls the air loading pressure to the device I8| and a valve I88 controls the pressure to the valve 94. Thus either 94or I 8|, or both, may be actuated automatically from a positioning ofthe pilot stem 98. A hand actuated valve I89 is located in the fuelsupply line ahead of the automatic valve 94 to limit the maximumavailable fuel at the burner 2.

In operation, assuming that the mean density through the conversionsection remains constant, then any deviation in mean temperature fromdesired established value will shift the pilot 98 to vary therecirculation of flue gases, which will in turn vary the meantemperature through the conversion section and cause a movement of thebeam 84 to reset the pilot toward its previous position.

If for some reason such as pressure, rate of charge, or other variable,the mean density through the conversion section should vary, other thanthrough a change in temperature, then I would want to establish a newmean temperature to work to. This is done by virtue of the fact that thechange in mean density causes a positioning of the point 11, which isturn positions the pilot 98 toshift the speed of the fan I82, and thusvary thetemperature which is observed by the pointer 8|.

It is desired that the hand valve I89 on the fuel supply be so adjustedthat the basic maximum supply of fuel and rate of firing may bepredetermined. For example, assume that the valve I89 is so positionedas to have a maximum availability of 80% total fuel supply. It isdesired that the operation normally be in some range of say 75-80%maximum available fuel, and only if the basic rate of operation of thestill is to be changed is the hand valve I 89 changed to shift thiscontrollable range. The design is such that full range of travel of thevalve 94 would be, for example, over'a range of 75-80% available fuel,or 65-70%, etc. If normal operation is slightly below the maximum of sayavailable fuel, and as the relation of tem-

